[PATCH 1/8] serial: st-asc: Ignore the parity error bit if 8-bit mode is enabled

Lee Jones
2017-01-24T13:43:03Z

The datasheet states:

"If the MODE field selects an 8-bit frame then this [parity error] bit
is undefined. Software should ignore this bit when reading 8-bit frames."

Signed-off-by: Lee Jones <lee.jones-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
---
drivers/tty/serial/st-asc.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c
index 379e5bd..69e6232 100644
--- a/drivers/tty/serial/st-asc.c
+++ b/drivers/tty/serial/st-asc.c
@@ -287,9 +287,19 @@ static void asc_transmit_chars(struct uart_port *port)
static void asc_receive_chars(struct uart_port *port)
{
struct tty_port *tport = &port->state->port;
- unsigned long status;
+ unsigned long status, mode;
unsigned long c = 0;
char flag;
+ bool ignore_pe = false;
+
+ /*
+ * Datasheet states: If the MODE field selects an 8-bit frame then
+ * this [parity error] bit is undefined. Software should ignore this
+ * bit when reading 8-bit frames.
+ */
+ mode = asc_in(port, ASC_CTL) & ASC_CTL_MODE_MSK;
+ if (mode == ASC_CTL_MODE_8BIT || mode == ASC_CTL_MODE_8BIT_PAR)
+ ignore_pe = true;

if (port->irq_wake)
pm_wakeup_event(tport->tty->dev, 0);
@@ -299,8 +309,8 @@ static void asc_receive_chars(struct uart_port *port)
flag = TTY_NORMAL;
port->icount.rx++;

- if ((c & (ASC_RXBUF_FE | ASC_RXBUF_PE)) ||
- status & ASC_STA_OE) {
+ if (status & ASC_STA_OE || c & ASC_RXBUF_FE ||
+ (c & ASC_RXBUF_PE && !ignore_pe)) {

if (c & ASC_RXBUF_FE) {
if (c == (ASC_RXBUF_FE | ASC_RXBUF_DUMMY_RX)) {
--
2.10.2

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